Vacuum delay valve

ABSTRACT

An improved engine spark timing control device that includes an elastic valve disc cooperating with a valve seat, such elastic valve disc having a fixed orifice therethrough. The control device operates to control the rate of change of application of sparking from the spark port to the servo means associated at the engine distributor. Another aspect of the invention is the improved manner of fabricating the elastic valve disc with a precise small area opening therein.

United States Patent [191 Scott, Jr.

[ Sept. 2, 1975 VACUUM DELAY VALVE [75] Inventor: Milford M. Scott, Jr.,Oak View,

Calif.

[73] Assignee: STP Corporation, FtQLauderdale,

Fla.

[22] Filed: Nov. 7, 1973 21 Appl. No.: 413,450

[52] US. Cl.... 123/117 A; 123/117 R; 123/146.5 R [51] Int. Cl. FOZP5/10 [58] Field of Search 123/117 A, 117 R, 146.5 A

[56] References Cited UNITED STATES PATENTS 3,007,987 11/1961 Barnes123/146.5 A X 3,234,929 2/1966 Sarg 123/146.5 A 3,326,197 6/1967 Elkins123/117 A 3,606,871 9/1971 Gropp et a1 123/117 A 3,678,907 7/1972Vartanian 123/117 A 3,804,326 4/1974 Mclntire 123/1 17 A X 3,812,8315/1974 Scott, Jr 123/117 A 3,857,373 12/1974 Martin et a1. 123/117 APrimary Examiner-Charles .1. Myhre Assistant Examiner-T0ny ArgenbrightAttorney, Agent, or Firm-Seymour Rothstein ABSTRACT An improved enginespark timing control device that includes an elastic valve disccooperating with a valve seat, such elastic valve disc having a fixedorifice therethrough. The control device operates to control the rate ofchange of application of sparking from the spark port to the servo meansassociated at the engine distributor. Another aspect of the invention isthe improved manner of fabricating the elastic valve disc with a precisesmall area opening therein.

8 Claims, 5 Drawing Figures VACUUM DELAY VALVE BACKGROUND OF THEINVENTION This invention relates to an engine spark timing controldevice, and more particularly, to an improved engine spark timingcontrol device which incorporates an elastic valve disc cooperating witha valve seat, such elastic valve disc cooperating with a valve seat,such elastic valve disc having fixed area orifice means therethrough.

Most automobile engines are today provided with a vacuum mechanism forautomatically controlling the advance or retard setting of the enginedistributor breaker plate as a function of the carburetor spark portvacuum so as to provide good engine performance, as well as fuel economyduring the different operating conditions of the vehicle engine. Thevacuum mechanism or servo comprises basically a housing divided into anatmospheric pressure chamber and a vacuum chamber by a flexiblediaphragm operatively connected to the distributor breaker plate. Theflexible diaphragm and the distributor breaker plate are normally springbiased to the lowest advance or retard spark timing setting, and thecarburetor spark port vacuum will normally urge the diaphragm in a sparktiming advance direction upon opening of the carburetor throttle valveto increase engine speed.

During rapid accelerations, the drop in vacuum at the carburetor sparkport permits atmospheric pressure acting on the opposite side of theservo diaphragm to quickly move the distributor breaker plate to a loweradvanced setting to meet engine performance requirements. On the otherhand, upon return to normal operation and gradual reacceleration ordeceleration of the engine, an increase in vacuum at the carburetorspark port causes an immediate return movement of the vacuum servodiaphragm to a higher engine spark timing advance setting. This providesa longer burning time for the fuel mixture before the optimum top ornear top dead center position of the piston is obtained, generallyproviding the most desirable operation. However, this longer timepermits a built-up to high combustion temperatures and pressures, whichare undesirable insofar as the production of nitrogen oxides and otherundesirable pollutant elements are concerned.

In the Gropp et al U.S. Pat. No. 3,606,871 there is disclosed an enginespark timing control device that is disposed between the spark port ofthe carburetor and the vacuum servo of the distributor. Such controldevice includes a one-way check valve in parallel flow circuit withsintered metal flow restrictions or plugs. The one-way check valveconsists of a flapper movable forward or away from relatively largeports in a wall of the housing of the control device. The sintered metalplugs consist of randomly oriented metal particles compacted togetherunder pressure so as to provide open ings for fluid flow. The Gropp etal. patent recognized the problems of providing a conventional orificeof a small flow capacity in place of the sintered metal flowrestrictions and comments that such could not be feasibly made underproduction conditions. Gropp et al indicated that a small flow sizeorifice made in a conventional manner by merely providing a reduceddiameter passage would be easily plugged by dirt.

An object of the present invention is to provide an improved enginespark timing control device wherein the disadvantages and deficienciesof prior known constructions are obviated.

Another object of the present invention is to provide an engine sparktiming control means incorporating an elasticdisc having fixed orificemeans therein that are readily and inexpensively made in production.

A further object of the present invention is to provide an improvedengine spark timing control means comprising a vacuum delay valve with ahousing having an elastic valve disc therein provided with fixed orificemeans therethrough that is self-cleaning in use due to the resilience ofthe elastic valve disc and which seals against its seat without the needfor additional seals.

Yet another object of this invention is to provide an improved method ofmaking an elastic valve disc having a small area opening therein.

These and other object of the present invention will become moreapparent hereinafter.

BRIEF DESCRIPTION OF THE DRAWING There is shown in the attached drawingpresently preferred embodiments of the present invention wherein:

FIG. 1 is a perspective view of an engine incorporating the engine sparktiming control arrangement of the present invention;

FIG. 2 is a schematic view of the engine spark timing controlarrangement showing the vacuum delay valve in cross section;

FIG. 3 is an enlarged cross-sectional view of the vacuum delay valveshowing the elastic disc therein in a different operating position fromthat in FIG. 2;

FIG. 4 is a plan view of-the elastic disc in the vacuum delay valve ofFIGS. 2 and 3; and

FIG. 5 is an enlarged cross-sectional view of a modified vacuum delayvalve.

DETAILED DESCRIPTION OF THE PRESENT INVENTION Referring to FIGS 1 and 2,there is illustrated an engine I0 embodying the engine spark timingcontrol arrangement 12 of the present invention. The engine, being ofconventional design, is shown somewhat schematically. Engineincorporates the usual block 14, carburetor 15, air filter l6, anddistributor 18. The engine spark timing control arrangement 12incorporates the distributor vacuum line means 20 that communicates thecarburetor to the diaphragm 54 of the servo means 21 of the distributorl8 and the slow-fast rate control device 22 disposed within the vacuumline means to control the rate of change of application of vacuum fromthe spark port of the carburetor 15 to the servo means 21 of distributor18.

In FIG. 2 there is better illustrated the engine spark timing control ofthe present invention. The carburetor 15 (shown schematically) is of thedown draft type which includes the usual air-fuel induction passage 24with an atmospheric air inlet 26 at one end and connected to the engineintake manifold 28 at the other end. Passage 24 contains the usual fixedarea venturi 30 and a throttle valve 32. The throttle valve 32 isrotatably mounted on a part of the carburetor body across the passage 24in a manner to control the flow of the air-fuel mixture into the intakemanifold 28. Fuel would be inducted in the usual manner from a nozzle(not shown) projecting into or adjacent the venturi 30 in a knownmanner.

The throttle 32, shown in its engine idle speed position essentiallyclosing the induction passage 24, is rotatable to a nearly verticalposition essentially unblocking the passage 24. A spark port 35 isprovided at a point just above the idle position of the throttle valve32, to be transversed by the throttle valve 32 during its opening orpart throttle movement. This will change the vacuum level in the sparkport 35 as a function of the rotative position of the throttle valve 32,with the spark port 35 reflecting essentially atmospheric pressure inthe air inlet 26 upon closure of the throttle valve 32.

The source of vacuum can be from the carburetor through a spark port (asshown) or alternatively, there could be a carburetor connection belowthe throttle valve or a connection directly from the intake manifold tocommunicating line 20.

When communicating line is connected directly from distributor servemeans 21 to intake manifold 28, the vacuum pressure in the intakemanifold will] be transmitted to the servo at a slow rate whenincreasing and at a fast rate when decreasing. The result is a delay inthe application of higher vacuum to the servo means to advance the sparktiming, with no delay in the reduction of vacuum in the servo to retardthe timing when the vacuum decreases in the intake manifold.

The distributor 18 includes a breaker plate 36 that is pivotally mountedat 36 on a stationary portion of the distributor l8, and movable withrespect to cam 40. The cam 40 has eight peaks 42 corresponding to thenumber of cylinders in engine 10, each peak 42 cooperating with thefollower 44 of a breaker points set 46 to make and break the sparkconnection in a known manner, each one eighth (in this case) rotation ofcam 40. Pivotal movement of breaker plate 36 is counterclockwise sparkretard setting direction, or in a clockwise spark advance settingdirection, is provided by an actuator 48 operatively connected todiaphragm 54 in the housing 23 of vacuum servo housing 21.

The vacuum servo 21 may be of conventional construction incorporatinghollow housing 23, whose interior is divided into an atmosphericpressure chamber 50 and a vacuum chamber 52 by an annular flexiblediaphragm 54. The diaphragm 54 is fixedly secured to the actuator 48 andis biased to the right as viewed in FIG. 2 to a retard direction by acompression spring 55. Chamber 50 has an atmospheric or ambient pressurevent (not shown) while the chamber 52 is connected by a bore 56 to theline 20.

During engine-off and other operating conditions to be described,atmospheric pressure exists on both sides of the diaphragm 54,permitting the spring 55 to force the actuator 48 to the lowest advanceor a retard setting position. Application of vacuum to chamber 52 movesthe diaphragm 54 and the actuator 48 toward the left as viewed in FIG. 2to an engine spark timing advance position, by degree responsive to thechange in vacuum level.

Disposed within the line 20 is the vacuum delay valve 22 of the presentinvention. The vacuum delay valve 22 comprises a housing formed of twoparts or cup-shaped portions 59 and 60 that are preferably molded fromplastic and bonded to one another. Extending through the housing bodypart 59 is a passage 62 having a valve seat 64 defined adjacent an endthereof. Disposed in the chamber 66 within the housing formed by thebody part 59 and cover part 60 is a resilient or elastic valve disc 68that is-adapted to seat against the valve seat 64. The elastic valvedisc 68 is biased toward the closed seating position against valve seat64 by spring means 70, which as shown may be fabricated frompolyurethane foam. In this case, the spring means 70 would also functionas a filter. Disposed in the passage 62 between the spark port and theelastic disc 68 is a filter 72, made from a suitable medium that willfilter out particles that might otherwise impede operation of the vacuumdelay valve.

Provided in the elastic valve disc 68 are orifice means of predeterminedfixed area. Whereas it has been suggested in the prior art that anorifice means of a fixed small flow capacity could not feasibly be madeunder production conditions, applicant has discovered that utilizationof a resilient valve disc having fixed area opening means formed thereincan be made under production conditions in an economical fashion.Because of the elasticity or resiliency of the disc it will properlyseat against the valve seat 64 and the flexibility thereof in use willhelp to free or unclog particles that might otherwise tend to accumulatein the fixed orifice mean therein.

In operation of the system, in engine-off, as well as engine idle speedand deceleration conditions, the engine spark port 35 will be atatmospheric pressure, as will both the chambers and 52 of the vacuumservo 21. Therefore, the distributor breaker plate 36 will be placed inits lowest engine spark timing advance or retard position by the servospring acting through actuator 48.

During part throttle engine operations, during normal depression of thevehicle accelerator pedal (not shown), rotation of throttle valve 32will communicate the vacuum in engine intake manifold 28 to the sparkport 35 so that the passage 62 will be at a pressure level lower thanthat on the opposite side of the elastic disc 68. As the elastic valvedisc 68 is seated, equalization of the pressures between the oppositesides of the valve disc will be obtained .only through the fixed orificemeans 69 in the valve disc 68. Thus, only a slow build up in vacuum willbe transmitted to the vacuum servo chamber 52, resulting in only a slowchange in the vacuum advance setting of the distributor breaker plate36. This is a slower response than the conventional engine spark timingcontrol system and the results in a lower advance setting thanconventional for the same vacuum level in spark port 35, therebyproducing lower peak combustion temperatures and pressures. The delayedignition also causes the mixture to continue burning into the exhaustsystem and thereby provides more complete combustion. The end result isa lower output of undesirable engine exhaust elements.

If the engine throttle valve is suddenly moved toward wide open throttleposition or rapid acceleration condition of operation, the sudden decayin vacuum in the engine intake manifold 28 is communicated immediatelythrough the spark port 35 to the passage 62 to the left of the elasticvalve disc 68. The vacuum level in the' line 20 to the right of theelastic valve disc 68 is at a vacuum level previously attained at thespark port 35 and therefore, is at a lower absolute pressure than thatin the passage 62. This immediately unseats the elastic valve disc 68(FIG. 3) and allows a quick equalization of the pressures on oppositesides of the disc valve. Ac cordingly, the immediate change in vacuumlevel in spark port 35 is promptly communicated to the servo chamber 52and the-braker plate 35 is immediately pivoted to a lower advancesetting more appropriate to an accelerating condition .of operation.

As soon as equalization occurs the slow increase in vacuum in the sparkport 35 permits the higher pressure in the chamber to the right of theelastic valve disc 68 to seat the elastic valve disc 68 and providecontinued advance at a delayed rate because of the restricted flowthrough the orifice means'69.'For each vacuum level of an engine, thereis a corresponding desirable engine spark timing setting that is bestfor the particular engine to provide optimum performance.

If the vehicle throttle valve 32 now is permitted to return toward or toits idle speed position, from the rapid acceleration position previouslyattained, the vehicle then begins driving the engine and the spark portvacuum immediately decays to a lower value than normal (a higherabsolute pressure than previously and higher than in the servo chamber52). This immediately opens the check valve 68 and permits a quickequalization of the vacuum servo chamber 52 pressure to that of thespark port pressure level to reduce the advance setting of thedistributor to a lower engine operating setting. Once the pressurelevels are equalized, the check valve 68 will again be seated.

There has been provided by the present invention an engine spark timingcontrol arrangement incorporating a vacuum delay valve that quickly andautomatically provides the desired spark timing setting for engineperformance and yet reduced the output of undesirable exhaust pollutantsby delaying normal advance timing during gradual part throttle engineaccelerating conditions of operation.

In FIG. 4 there is shown a plan view of an elastic valve disc 68incorporating a single fixed area opening 69. The opening 69 is formedwith precision and in one embodiment of the invention the opening is onthe order of 0.0025 inch in diameter. The opening 69 is preferablyformed by tensioning or compressing the material of disc 68 to reducethe effective thickness at the center thereof, forming the hole (orholes) using an oversized punch, drill or laser beam of predeterminedsize, and then releasing the tension or compression to permit the discmaterial to return to its unstressed state to provide a hole (or holes)of the desired area for the particular engine requirements with whichthe vacuum delay valve is used. Tensioning can be accomplished byclamping the edges peripherally and drawing the edges outwardlyQThe discmaterial can be compressed in dies and then punched, drilled, or laseredthrough a suitable opening in a die. By use of oversized means forforming the opening of predetermined size, greater precision ispossible. This method results in an elastic disc with a precision formedsmall area opening that is able to be produced consistently inproduction in an economical fashion.

With reference to FIG. 5 there is illustrated a modification of thepresent invention. which functions in all respects like the embodimentof FIGS. 2 and 3, but wherein the spring means 70 is in the form ofaconventional coil spring 170 rather than the polyurethane spring of theembodiment of FIGS. 2 and 3.

Preferablythe vacuum delay valve 22 of the present invention isfabricated from inexpensive components, such as plastic. so that after apredetermined operational use. the vacuum delay valve can be discardedand a new valve substituted therefor.

One or more openings 69 may be provided in elastic disc 68. Further adifferent sized fixed orifice (or orifices)69 may be provided in theelastic disc 68 to accomodate the requirements of different engines. Themethod of manufacture described herein produces 'a superior .elasticdisc product'that can be made with consistancy'and" uniformity inproduction.

While I have shown presently preferred embodiments of the presentinvention, it will be obvious that other embodiments may be made withinthe scope of the appended claims.

What is claimed is:" r

1. In a spark timing control system comprising an engine carburetorhaving an induction passage containing a spark port located above theidle speed position of a throttle valve controlling flow through theinduction passage and subject to the depression in the carburetor as afunction of the movement of the throttle valve from its idle speedposition, an engine distributor having a breaker plate typically movablein opposite directions to advance and retard the spark timing,vacuumcontrolled servo means connected to said breaker plate for movingthe same, and slow-fast rate control means between said spark port andservo means to control the rate of change of application of vacuum fromsaid spark port to said servo means, said control means in cludingfaster flow rate means operable in response to a change in thedepression at said spark port to a lesser depression than at said servomeans to quickly equalize the pressure level at said servo means to thatat the spark port, and slower flow rate means operable in response to achange in the depression at said spark port to a greater depression thanat the servo means to delay the equalization of the pressure level atthe servo means to that at the spark port to delay the spark timingchange, said control means including conduit means connecting said sparkport to said servo means, said control means comprising a vacuum delayvalve in said conduit means having a passage therethrough with anannular seat, said faster flow rate means comprising an elastic disccooperating with said annular seat and said slower flow rate meanscomprising fixed orifice means in said elastic disc, said fixedorifice'means comprising at least one opening through the elastic discto provide a controlled delay in pressure change to the servo means,said opening being self-cleaning in use because of the resiliency of theelastic disc and the movement thereof in use.

2. The mechanism of claim 1 wherein a filter is disposed in the vacuumdelay valve between the spark port and the elastic disc.

3. The mechanism of claim 1 including spring means for biasing theelastic disc into engagement with the annular seat.

4. The mechanism of claim 3 wherein the spring means comprises resilientplastic.

5. The mechanism of claim 3 wherein the spring means is disposed betweenthe elastic disc and the engine distributor.

6. The mechanism of claim 1 wherein the vacuum delay valve comprises ahousing comprised of a body and a cover, a filter in the housing betweenthe spark port and the elastic disc. and spring means associated withthe elastic disc for biasing the elastic disc toward the annular seat.

7. The mechanism of claim 6 wherein the fixed orifice means in theelastic disc comprises at least two fixed area openings the openingsbeing self-cleaning because of the movement of the elastic disc andtheresiliency thereof. 7 v I 8. In a spark timing control system comprisingan engine distributor having a breaker plate movable in' oppositedirections to advance and retard the spark timing and communicating withan engine source of vacuum, vacuum-controlled servo means connected tosaid breaker plate for moving the same, and control means between saidengine source of vacuum and servo means to control the rate of change ofapplication of vacuum from the engine source of vacuum to said servomeans, said control means including a conduit connecting said enginesource of vacuum to said servo means and a vacuum delay valve in saidconduit means having apassage therethrough with an annular seat, anelastic disc cooperating with said annular seat and movable 1 theresiliency thereof.

1. In a spark timing control system comprising an engine carburetorhaving an induction passage containing a spark port located above theidle speed position of a throttle valve controlling flow through theinduction passage and subject to the depression in the carburetor as afunction of the movement of the throttle valve from its idle speedposition, an engine distributor having a breaker plate typically movablein opposite directions to advance and retard the spark timing,vacuumcontrolled servo means connected to said breaker plate for movingthe same, and slow-fast rate control means between said spark port andservo means to control the rate of change of application of vacuum fromsaid spark port to said servo means, said control means including fasterflow rate means operable in response to a change in the depression atsaid spark port to a lesser depression than at said servo means toquickly equalize the pressure level at said servo means to that at thespark port, and slower flow rate means operable in response to a changein the depression at said spark port to a greater depression than at theservo means to delay the equalization of the pressure level at the servomeans to that at the spark port to delay the spark timing change, saidcontrol means including conduiT means connecting said spark port to saidservo means, said control means comprising a vacuum delay valve in saidconduit means having a passage therethrough with an annular seat, saidfaster flow rate means comprising an elastic disc cooperating with saidannular seat and said slower flow rate means comprising fixed orificemeans in said elastic disc, said fixed orifice means comprising at leastone opening through the elastic disc to provide a controlled delay inpressure change to the servo means, said opening being self-cleaning inuse because of the resiliency of the elastic disc and the movementthereof in use.
 2. The mechanism of claim 1 wherein a filter is disposedin the vacuum delay valve between the spark port and the elastic disc.3. The mechanism of claim 1 including spring means for biasing theelastic disc into engagement with the annular seat.
 4. The mechanism ofclaim 3 wherein the spring means comprises resilient plastic.
 5. Themechanism of claim 3 wherein the spring means is disposed between theelastic disc and the engine distributor.
 6. The mechanism of claim 1wherein the vacuum delay valve comprises a housing comprised of a bodyand a cover, a filter in the housing between the spark port and theelastic disc, and spring means associated with the elastic disc forbiasing the elastic disc toward the annular seat.
 7. The mechanism ofclaim 6 wherein the fixed orifice means in the elastic disc comprises atleast two fixed area openings the openings being self-cleaning becauseof the movement of the elastic disc and the resiliency thereof.
 8. In aspark timing control system comprising an engine distributor having abreaker plate movable in opposite directions to advance and retard thespark timing and communicating with an engine source of vacuum,vacuum-controlled servo means connected to said breaker plate for movingthe same, and control means between said engine source of vacuum andservo means to control the rate of change of application of vacuum fromthe engine source of vacuum to said servo means, said control meansincluding a conduit connecting said engine source of vacuum to saidservo means and a vacuum delay valve in said conduit means having apassage therethrough with an annular seat, an elastic disc cooperatingwith said annular seat and movable toward and away therefrom to controlflow through the passage, and fixed orifice means of predetermined sizein said elastic disc, said fixed orifice means comprising an openingthrough the elastic disc that is self-cleaning in use because of themovement of the elastic disc and the resiliency thereof.